This blog has been set up for editors, reviewers, authors and readers of Elsevier's Analytical Chemistry Journals - all of which can be seen below. It will be updated from Monday to Friday with general news and announcements concerning the titles listed on this page. It should be noted that the views or claims made in the news items and feeds are not necessarily those of the Publisher.

1 March 2013Publication year:
2013Source:Sensors and Actuators A: Physical, Volume 191The
phase carrier signal of the PGC demodulation in fiber optic interferometric
sensors (FOIS) may be generated by using laser current modulation to achieve
all-fiber structures in long-distance and outdoor applications. An optical
intensity modulation with carrier frequency induced from the laser modulation
will cause the instability and distortion in the PGC demodulation output.
Additionally, since the optical intensity attenuation of the FOIS will degrade
the PGC demodulation output, proper sensitivity compensation on the PGC
demodulator is necessary for the field applications. In this paper, we propose
an improved technique by using a balanced photoreceiver in the FOIS to attain
significant improvements in the instability and distortion of the PGC
demodulation output. Moreover, we choose a small phase scrambler signal
amplitude of 1rad to achieve improved the minimum phase detection sensitivity
(MPDS) as well as sensitivity normalization because the improvement of the MPDS
is very important to the advanced FOIS. The experimental results show that the
improved values of the best MPDS are 5.7dB (for DFB laser diode) and 4.3dB (for
EP1550 laser diode), respectively, by using the improved technique. From the
sensitivity normalization experiment results, the relative error is shown to be
less than 0.5% when the optical intensity attentuation is no more than 15dB. It
verifies the effectiveness of the sensitivity normalization technique proposed
in our improved PGC demodulation system.

1 February 2013Publication year:
2013Source:Sensors and Actuators A: Physical, Volume
190Ferrule-top micro mechanical sensors are an alternative platform for
point measurements in critical environments, where standard
micro-electro-mechanical systems are prone to failure. To fully benefit from the
all-optical character of this design, it is important to demonstrate that the
mechanical pieces fabricated on top of the ferruled fiber can be actuated with
light. In this paper we propose a convenient, all-optical actuation scheme that
can be applied without any additional modification of the sensor design. The
scheme relies on the photo thermal effect, which is proven to be sufficient both
for inducing significant static bending and for exciting the sensor to
resonance. We also demonstrate that this mechanism can be successfully used to
implement ferrule-top resonant sensors for humidity and pressure measurements.

Highlights

► We demonstrate an all-optical actuation scheme for
ferrule-top sensors. ► The new approach does not require any modification of
sensors design. ► The method is sufficient for static and dynamic excitation. ►
We present an all-optical gravimetric humidity and pressure
sensor.

A
novel and simple optical fiber structure with a section of no-core fiber for
measuring relative humidity (RH) is presented. Moisture-sensitive materials
HEC/PVDF are used to form the hydrogel coating on the no-core fiber by dip
impregnation method. Under different humidity conditions, the humidity induced
refractive index changes on the outside coating of no-core fiber will lead to
the variations of the optical output power. The different lengths of no-core
fiber are tested at the two wavelengths of 1310nm and 1550nm, respectively. The
results show that the structure with 2cm no-core fiber has a higher RH
sensitivity of 0.196dB/%RH at 1310nm and a better linearly response when the RH
is lower than 75%. Furthermore, the optical output powers are measured with the
rise and drop of RH, and the four times repetition are also recorded, which all
demonstrate the good stability and repeatability of our proposed structure.

This
paper investigates the temperature dependence of the resonance frequency for
locally heated cantilever beams and proposes a solution to minimize it. In the
first part of the paper a theoretical study, supported by simulations, is
carried out in order to determine the temperature distribution on locally heated
cantilever beams. The theoretical results are supported by measurements
performed with an IR camera. Knowing the temperature distribution on the
cantilever beams, the frequency shifts due to the temperature gradient on the
beams is calculated. A comparison between three locally heated cantilever beams
made of Si, SiO2 and SiN shows that SiN is the best choice in order to minimize
the temperature dependence of the resonance frequency. Measurements on a SiN
cantilever paddle show that its resonance frequency is constant with heater
temperature for temperature up to 590 K. The device exhibits a temperature
dependence of the resonance frequency of about 20ppm/K, for heater temperature
from 590K to 920K.

A
measurement scheme to measure a composite material's thermal elongation induced
strain using a buffer stripped Polarization Maintaining Photonic Crystal Fiber
(PM-PCF) sensor is investigated in this paper. A composite material sample with
an embedded PM-PCF based polarimetric fiber sensor is fabricated and
characterized. It is found that the buffer stripped PM-PCF polarimetric sensor
which is temperature insensitive in free space, shows significant phase change
when embedded in the composite material due the thermal elongation of the
composite material. The temperature induced phase change of buffer stripped
PM-PCF polarimetric sensors embedded in carbon-epoxy, E glass-epoxy, E
glass-unsaturated polyester resin composite material samples is measured and the
results are used to determine the thermal elongation induced strain over a
temperature range from 0°C to 65°C. The experimentally measured thermal
elongation induced strain of the same samples are found to be
3.648×10−5 ɛ/°C, 1.52×10−5 ɛ/°C, and 2.42×10−5
ɛ/°C. The Coefficient of Thermal Expansion (CTE) estimated theoretically using
composite laminate theory shows good agreement with that derived using the
PM-PCF sensor. The present investigation offers a simple non destructive method
to determine thermal elongation induced strain in composite structures. It is
shown that the method allows the measurement of thermal expansion for those
composite materials having negligible residual strain and moisture expansion.

Position sensors with nanometer resolution are a key component of
many precision imaging and fabrication machines. Since the sensor
characteristics can define the linearity, resolution and speed of the machine,
the sensor performance is a foremost consideration. The first goal of this
article is to define concise performance metrics and to provide exact and
approximate expressions for error sources including non-linearity, drift and
noise. The second goal is to review current position sensor technologies and to
compare their performance. The sensors considered include: resistive,
piezoelectric and piezoresistive strain sensors; capacitive sensors;
electrothermal sensors; eddy current sensors; linear variable displacement
transformers; interferometers; and linear encoders.

A
transparent force sensing array with low power consumption is developed from a
3×3 liquid crystal (LC) array. As force is applied to the LC array, the
force-dependent capacitance curve of a sensor pixel under a higher voltage will
shift to larger capacitance. Accordingly, the force range of the LC array can be
divided into many sub-ranges at one of the capacitance values. The number of the
input voltage is equal to that of the output capacitance in each of the
sub-ranges, and the voltage-to-capacitance number is small (large) in the high
(low)-force sub-range. The sensing array measures force in terms of the
voltage-to-capacitance number. The transparent force sensing array shows
potential as a touch panel, while it is immune to the need of rectifying the
nonlinear relation between the applied force and the output capacitance using
complex algorithm via high-end microcontrollers.

Undoped and Sn-doped ZnO nanopowder samples were prepared by the
sol–gel method. The crystalline structure and surface morphology of the samples
were analyzed by X-ray diffraction and atomic force microscopy. X-ray
diffraction results indicate that the samples exhibit a hexagonal crystal
structure. Electrical properties of the samples were measured by two probe
method. The activation energies of the ZnO samples for low and high temperatures
regions were determined. The optical band gaps of the samples were determined by
optical absorption method. It was found that the samples have a direct
transition optical band gap and the optical band gap values of the ZnO samples
were changed with Sn doping. Quartz crystalline microbalance (QCM) technique was
employed to investigate sensor features of the ZnO samples. The humidity sensor
properties of undoped and Sn-doped ZnO samples based on quartz crystalline
microbalance sensors were investigated. The obtained results indicate that the
undoped and Sn-doped ZnO nanopowder samples can be used for humidity sensor
applications.

In
this paper, we report a significant piezoresistive effect found in ZnO
nanowires–polyimide nanocomposite. ZnO nanowires were synthesized through a
simple hydrothermal route and subsequently mixed with polyimide matrix to form
ZnO nanowires–polyimide nanocomposite. Electrical properties of the
nanocomposite films, such as electrical conductivity, relative dielectric
permittivity, impedance spectrum and electrical I–V curve, change with weight
ratio of ZnO nanowires were characterized. Electrical measurement results
indicated that the percolation threshold of the nanocomposite is about 15%
weight ratio of ZnO nanowires. Piezoresistive effect of the nanocomposite was
investigated and large gauge factor was observed for this nanocomposite. Strain
sensors based on the nanocomposite thin films using interdigital electrodes were
fabricated and used to measure the static and dynamic strain in a cantilever
beam and the results were validated by theoretical calculation and measurements
by other technique. With excellent flexibility, simple fabrication process, and
large piezoresistive gauge factor, this novel ZnO nanocomposite can be used for
strain sensors in many mechanical, civil, aerospace, and medical applications.

Multi-layered films of zinc oxide (ZnO), prepared using sol–gel
spin-coating method, were used to study the response on exposure to liquefied
petroleum gas (LPG). The X-ray diffraction (XRD) pattern of the thin films
showed preferred orientation of the crystallites along the c-axis. Surface
morphology studies using scanning electron microscopy (SEM) reveal a wrinkled
surface with a worm like appearance for the film thickness varying from 85nm to
419nm. The films of different thickness were exposed to LPG and sensing
characteristics were recorded using electrical methods. The ZnO thin films
showed good sensitivity toward LPG at optimum temperature of 200°C with
sensitivity strongly depending on the number of layers deposited. The sensing
characteristics were further correlated with the microstructure of the thin
films investigated using atomic force microscopy (AFM).

VICI Metronics’ Dynacalibrator® Model 150is a constant temperature system designed to
generate precise ppm or ppb concentrations of chemical compounds in a gas
stream, using permeation devices as the trace gas source. It is used as a
reference for the calibration of gas chromatography instruments and in other
instruments that measure gas concentrations.

This light-weight unit is a compact calibrator capable of
delivering the precise concentrations required. A passivated Inertium® coated
stainless steel permeation chamber houses the permeation device(s), with
measured inert carrier gas sweeping the calibration gas/vapor from the chamber.
The digital temperature controller maintains the chamber temperature at a set
point with an accuracy of ±0.01°C, traceable to NIST standards. The wide range
of temperature settings (5°C above ambient to 110°C) means the end user can
generate a wide range of volumetric concentrations for both low and high vapor
pressure chemical compounds, establishing or changing the desired volumetric
concentration by simply varying the carrier flow. Reduced flow path volume
permits low concentration generation of mercury, water and other difficult to
work with materials.

Multicomponent mixtures can be easily generated with a
Dynacalibrator and the appropriate combination of permeation devices. This
technique also allows the removal of a single component from a gas mixture by
simply removing the appropriate permeation device. Users have a choice of
plumbing and flow configurations. This unit also permits remote control via RS
232 cable.

Warner
Instruments is pleased to introduce the Bold Line CO2 - O2
Gas Controllers, part of the complete line of gas controllers from Okolab.
Warner Instruments is the Authorized Distributor for Okolab products in the US.

Digitally controls O2 and CO2
concentration

Fully integrated with Bold Line Temperature
Controllers

The
Bold Line combination CO2 - O2 gas controllers are ideal
for hypoxia and hyperoxia experiments. Two versions are available, CO2;
0-10% and O2; 1-18%, and CO2; 0-20% and O2;
1-95%.

Operation
is via an easy to use touch screen interface, OKO-Touch. An optional Smart Box
data logger and web server allows operation via any web-enabled device. The
system may also be operated via a PC using OKO-Control 2.0 software or Nis
Elements software.

Warner
Instruments
is a designer and manufacturer of biomedical devices for the
electrophysiological, cellular and neurological sciences.

Home-based collection protocols for clinical
specimens are actively pursued as a means of improving life quality of patients
that require frequent controls, such as patients with metallic prosthesis, for
whom monitoring the evolution of Mo and Ti in biological fluids may play a
decisive role to detect prosthesis mal-functioning. The collection of biological
fluids on clinical filter papers provides a simple way to implement these
protocols. This work explores the potential of solid sampling high-resolution
continuum source graphite furnace atomic absorption spectrometry for the
simultaneous and direct determination of Mo and Ti in urine, after its
deposition onto clinical filter paper, giving rise to a dried urine spot. The
approach used for depositing the sample was found crucial to develop a
quantitative method, since the filter paper acts as a chromatographic support
and produces a differential distribution of the target analytes. Furthermore,
the high spreading of urine onto a filter paper results in a small amount of
urine per surface unit, and thus, ultimately, in lack of sensitivity. In order
to circumvent these problems, the use of an alternative approach based on the
use of pre-cut 17x19 mm filter paper pieces onto which larger amounts of sample
(500 μL) can be retained by single deposition was proposed and evaluated. In
this way, an approximately 12-fold increase in sensitivity and a more
homogeneous distribution of the target analytes were obtained, permitting the
development of a quantification strategy based on the use of matrix-matched
urine samples of known analyte concentrations, which were subjected to the same
procedure as the samples. Accuracy of this method, which provides LODs of
1.5μgL-1 for Mo and 6.5μgL-1 for Ti, was demonstrated
after analysis of urine reference materials. Overall, the performance of the
method developed is promising, being likely suitable for determination of other
analytes in dried urine spots.

Highlights

► deposition of urine on clinical filters is a
simple way to implement home-base collection procedures to monitor patient's
evolution ► solid sampling HR CS GFAAS is investigated for the direct
determination of Mo and Ti, used as biomarkers to detect prosthesis
malfunctioning, in urine dried spots; ► the way in which the sample is deposited
in the filter is key to ensure sufficient sensitivity and to avoid
chromatographic effects; ► use of matrix-matched urine standards for calibration
is proposed, permitting achieving accurate results and LODs of a few
μgL-1;

Interferences of selected hydride forming elements
(As, Sb, Bi, Se and Sn) on lead determination by hydride generation atomic
absorption spectrometry were extensively studied in both on-line atomization and
preconcentration (collection) modes. The commonly used on-line atomization mode
was found free of significant interferences, whereas strong interference from Bi
was observed when employing the preconcentration mode with plumbane collection
in a quartz trap-and atomizer device. Interference of Bi seems to take place in
the preconcentration step. Interference of Bi in the collection mode cannot be
reduced by increased hydrogen radical amount in the trap and/or the atomizer.

Highlights

► Interference study on Pb determination by
in-atomizer trapping was performed for the first time. ► Bi was found as a
severe interferent in the preconcentration mode (Pb:Bi ratio 1:100). ► No
interference was found in the on-line atomization (no preconcentration). ► Bi
interference occurs during preconcentration.

This article summarizes measurements and analysis of
hydrogen Balmer series atomic lines following laser-induced optical breakdown.
Electron number density on the order of 1 × 1025 m−3 can
be measured using H α Stark width and shift in the analysis of breakdown plasma
in 1 to 1.3 × 105 Pa, gaseous hydrogen. The H β line can be utilized
for electron number density up to 7 × 1023 m−3. The
historic significance is elaborated of accurate H β measurements. Electron
excitation temperature is inferred utilizing Boltzmann plot techniques that
include H γ atomic lines and further members of the Balmer series. Laser
ablation of aluminium is discussed in view of limits of application of the
Balmer series. H β and H γ lines show presence of molecular carbon in a 2.7 and
6.5 × 105 Pa, expanding methane flow. Diagnostic of such diatomic
emission spectra is discussed as well. Laser-induced breakdown spectroscopy
historically embraces elemental analysis, or atomic spectroscopy, and to a
lesser extent molecular spectroscopy. Yet occurrence of superposition spectra in
the plasma decay due to recombination or due to onset of chemical reactions
necessitates consideration of both atomic and molecular emissions following
laser-induced optical breakdown. Molecular excitation temperature is determined
using so-called modified Boltzmann plots and fitting of spectra from selected
molecular transitions. The primary interest is micro-plasma characterization
during the first few micro-seconds following optical breakdown, including
shadowgraph visualizations.

In this work, the possibility of using Laser-Induced
Breakdown Spectrometry (LIBS) combined with liquid–liquid microextraction
techniques is evaluated as a simple and fast method for trace elemental
analysis. Two different strategies for LIBS analysis of manganese contained in
microdroplets of extraction solvent (Triton X-114) are studied: (i) analysis by
direct laser irradiation of microdroplets; and (ii) analysis by laser
irradiation of microdroplets dried on metallic substrates (surface-enhanced LIBS
— SENLIBS). Experiments were carried out using synthetic samples with different
concentrations of manganese in a 10% w/w Triton X-114 matrix. The analysis by
direct laser irradiation of microdroplets showed low precision, sensitivity and
poor linearity across the concentration range evaluated (R2
<0.95). On the other hand, the SENLIBS method of analysis improved the
sensitivity, the precision and the linearity of the calibration curve with
respect to the direct analysis of microdroplets. In comparison with experimental
results obtained by direct analysis, SENLIBS also allowed several replicate
measurements to be carried out in a single microdroplet. The limit of detection
obtained was 6μgg−1 of Mn.

Highlights

► LIBS combined with microextraction procedures for
trace analysis is proposed. ► The proposed combination depends on LIBS ability
to analyze sample microvolumes. ► A surface-enhanced LIBS methodology for
microdroplet analysis was evaluated. ► Results indicate this combination to be
promising for trace analysis in liquids.

The presence of self-absorption of emission lines is
usually an undesired effect in Laser Induced Breakdown Spectroscopy because it
introduces non linear effects in the growth of line intensity versus the
concentration of the emitting species. Several methods have been proposed in
recent years for identifying and quantifying self-absorption in the emission
spectra. After this diagnostic stage, the lines affected by self-absorption are
usually disregarded; otherwise, appropriate corrective factors are applied to
their intensity before the utilization for analytical purposes. Changing the
point of view, this paper remarks as self-absorption can provide useful
information for analyzing the composition of laser-induced plasmas and for their
characterization. Whenever the extent of self-absorption is quantified, in fact,
the optical depth of the line can be rapidly calculated; then, for plasmas in
local thermodynamic equilibrium conditions, the columnar density of the emitting
species can be derived. Assuming the plasma homogeneity, the concentration ratio
between different elements can be obtained. Moreover, in particular cases, the
columnar densities can be used to calculate the plasma temperature and the
absolute number densities of plasma species. Some applications of the method are
reported in the paper and potentialities and limitations are discussed.

Highlights

► A method for LIBS plasma characterization based on
self absorption is presented. ► It allows to calculate absolute columnar number
densities of plasma species. ► It allows also to calculate plasma temperature
and analytical composition. ► The method does not rely on the spectral
calibration of the detection apparatus.

Chlorine is a main elemental component of atmospheric
particulate matter (APM). The knowledge of the chemical form of chlorine is of
primary importance for source apportionment and for estimation of health effects
of APM. In this work the applicability of high-resolution wavelength dispersive
proton induced X-ray emission (PIXE) spectroscopy for chemical speciation of
chlorine in fine fraction atmospheric aerosols is studied. A Johansson-type
crystal spectrometer with energy resolution below the natural linewidth of Cl K
lines was used to record the high-resolution Kα and Kβ proton induced spectra of
several reference Cl compounds and two atmospheric aerosol samples, which were
collected for conventional PIXE analysis. The Kα spectra which refers to the
oxidation state, showed very minor differences due to the high electronegativity
of Cl. However, the Kβ spectra exhibited pronounced chemical effects which were
significant enough to perform chemical speciation. The major chlorine component
in two fine fraction aerosol samples collected during a 2010 winter campaign in
Budapest was clearly identified as NaCl by comparing the high-resolution Cl Kβ
spectra from the aerosol samples with the corresponding reference spectra. This
work demonstrates the feasibility of high-resolution PIXE method for chemical
speciation of Cl in aerosols.

Highlights

► Chemical specation of Cl in aerosol samples by
high resolution PIXE spectroscopy. ► Fine structure of Kα and Kβ lines of
reference compounds and APM samples was given. ► Kα spectra were well aligned
with each other confirming the same Cl oxidation state. ► Pronounced chemical
effects were observed in the Kβ spectra. ► We showed that chemical speciation of
Cl was possible on thin aerosol samples.

BVT Technologies has launched the USB
POTENTIOSTAT which opens new field of electrochemical devices. The device
is compatible with AC1 sensors with integrated microreactor. The device
contains the amperommetry, cyclic voltammetry and puls amperommetry. It is
convenient for fast screening electrochemical measurement via USB.

TWO-CHANNEL
VOLTMETER The device is destinated for two channel (x, y)
recording of low DC signals or slowly changing voltages in range 0 – 5,000 V
with resolution 0,1mV. The minimum sampling time is 50 ms. The device is
connected by USB which also supply the device. The size of device is of USB
memory stick. The analog inputs are protected agains change of polarity and
against overload.

Available from Uniqsis Ltd. the FlowSyn Polar Bear™ is a state-of-the-art
chiller unit which, in combination with FlowSyn Continuous Flow Reactor, allows
you to perform and control reactions down to -88°C.

The FlowSyn Polar Bear™ provides faster and more efficient cooling than
conventional chiller units and is ideal for pre-cooling reagents and
controlling temperature in highly exothermic reactions. The system is
compatible with the FlowSyn range of reactor modules and is designed to prevent
ice formation so that you can clearly observe reactions as they occur.

Traditionally equipment for cooling flow chemistry reactions below -70°C has
been cumbersome and inconvenient, involving pressurised gas cylinders and/or
heat exchangers. With its fully integrated plug-and-play design, the Polar
Bear™ is both easy to install and simple to operate, as well as providing
superb cooling performance. The Polar Bear™ uses advanced cooling technology
without the need for solid CO2, solvents or heat transfer fluids to deliver
rapid cooling down to -88°C at the simple touch of a button.

The Polar Bear™ module is
compatible with all Uniqsis coil reactors and mixer blocks and works in
combination with and can be controlled by any FlowSyn flow reactor system. For
highly exothermic reactions the Polar Bear Plus module is additionally compatible with Uniqsis’ proprietary mixer /
reactor chip technology.

In this study, an efficient strategy based on bioassay-guided
fractionation, high-performance liquid chromatography/electrospray ionization
quadrupole time-of-flight mass spectrometry (HPLC-ESI-Q/TOF-MS) and high-speed
counter-current chromatography (HSCCC) was established to screen and purify
bioactive compounds from Chinese herbal medicines (CHMs). This screening system
was efficient and successfully applied to reveal anti-prostate cancer candidates
from Puerariae thomsonii Flos. As a result, an active fraction with strong in
vitro anti-prostate cancer activity was obtained, and the main compounds in the
fraction were purified by HSCCC, giving 82mg of tectoridin, 36mg of
tectorigenin-7-O-[β-d-xylopyranosyl-(1→6)-β-d-glucopyranoside and 64mg of
tectorigenin. Among them, tectorigenin, possessing the highest anti-prostate
cancer activity with IC50 value of 0.08μM, has priority to be lead compound. The
results of this work demonstrated that the developed method was efficient and
could be employed for the rapid screening, identification and purification of
active components from CHMs.

Graphical abstract

Highlights

► An efficient strategy
based on bioassay-guided fractionation, HPLC-ESI-Q/TOF-MS and HSCCC was
established to screen and purify bioactive compounds from CHMs. ► The screening
system succeeded in discovering anti-prostate cancer candidates from Puerariae
thomsonii Flos. ► Tectoridin,
tectorigenin-7-O-[β-d-xylopyranosyl-(1→6)-β-d-glucopyranoside and tectorigenin
were prepared from Puerariae thomsonii Flos by HSCCC for the first time. ►
Tectorigenin possessed potent inhibition effect on growth of RM-1 prostate
cancer cells with IC50 value of 0.08μM.

Dimethyl sulfate (DMS) is frequently used in pharmaceutical
manufacturing processes as an alkylating agent. Trace levels of DMS in drug
substances should be carefully monitored since the compound can become an
impurity which is genotoxic in nature. Derivatization of DMS with dibenzazepine
leads to formation of the N-methyl derivative, which can be retained on a
reversed phase column and subsequently separated from other potential
impurities. Such derivatization occurs relatively slowly. However, it can be
substantially speed up if ionic liquids are used as reaction media. In this
paper we report the use of 1-butyl-1-methylpyrrolidinium
bis(trifluoromethylsulfonyl)imide (IL1) and 1-butyl-4-methylpyridinium
tetrafluoroborate (IL2) as reaction media for the derivatization of DMS with
dibenzazepine. It was determined that the stoichiometry between the substrate
and DMS may be 1:1 or 2:1, in relation with the nature of the reaction media. An
(+)ESI-MS/MS approach was used for quantitation of the derivatized product.
Alternatively, DMS derivatization may be carried out with pyridine in
acetonitrile (ACN). The N-methylpyridinium derivative was separated by
hydrophilic interaction liquid chromatography (HILIC) and detected through
(+)ESI-MS (in the SIM mode). In both cases, a limit of quantitation (LOQ) of
0.05μg/ml DMS was achievable, with a linearity range up to 10μg/ml. Both
analytical alternatives were applied to assay DMS in 4-(2-methoxyethyl)phenol,
which is used as a starting material in the synthesis of metoprolol.

Graphical abstract

Highlights

► LC/MS–MS analysis at
sub-ppm level of dimethyl sulfate in starting materials for APIs is proposed. ►
Derivatization of DMS with dibenzazepine or pyridine was achieved. ►
Derivatization kinetics was studied in acetonitrile and ionic liquids
(pseudo-first-order). ► Derivatization with dibenzazepine in ionic liquids is
much faster than in acetonitrile. ► RPLC (for N-methyl-dibenzazepine) and HILIC
(for N-methyl-pyridine) separation modes were used.

This paper presents the development of a new method for the simple and
reliable quantification of the free drug amount in liposomal preparations of
prednisolone phosphate (PP). In this method the free drug is distinguished from
the encapsulated drug by means of hydrolysis of the free PP into prednisolone
(P) by alkaline phosphatase (AP). During method development reaction progress
curves were recorded to determine the required AP concentration and the
corresponding incubation time to achieve hydrolysis of all free PP. Reaction
progress curves also showed that small changes in the amount of weighted AP and
the incubation periods used do not cause a change in outcome. Further, several
organic solvents were tested as precipitation solvent and the use of
tetrahydrofuran (THF) yielded clean chromatograms, rapid AP deactivation and
complete liposome rupture avoiding under- and overestimations of the
encapsulated and free drug concentrations. Method accuracy was evaluated during
a cross-validation involving dialysis. Intra- and interday precision were
evaluated by determining the standard deviation (SD) and relative standard
deviation (RSD) after applying the new method on one day (n =4) and on different
days (n =3). The accuracy of the developed method is comparable to the accuracy
determined by dialysis, while clearly the method using AP is more precise. In
conclusion, comprehensive method development yielded an accurate and precise
method, which can replace traditional methods like dialysis and solid phase
extraction (SPE). With little effort the method can be upgraded and become part
of the liposome certification prior to human use. The overall principle behind
the method offers possibilities for many drug carrier systems.

Highlights

► A method for the quantification of the free drug
amount in liposomal preparations of prednisolone phosphate was developed. ► The
free drug is distinguished from the encapsulated drug by means of enzymatic
hydrolysis. ► In this way difficulties accompanying traditional separation
techniques were circumvented. ► Thismethod is reliable, accessible,
inexpensive,fast and suitable for small sample volumes and a large number of
samples. ► The principle behind this method offers also possibilities for the
free drug determination of many drug carrier systems.

Nine polysaccharide-based chiral stationary phases (CSPs) were used to
define a separation strategy that combines normal-phase (NP), reversed-phase
(RP) and polar organic solvent chromatography (POSC) modes. After limiting
ourselves to two CSPs per mode, in total, five CSPs, Chiralpak AD (NP),
Chiralcel OD (RP and POSC), Lux Cellulose-1 (NP), Lux Cellulose-2 (POSC) and Lux
Cellulose-3 (RP), showed the broadest enantioselectivity and most
complementarity. Six sequences of the three modes were considered to decide
which sequence is the most successful for screening a set of 56 pharmaceutical
compounds. Starting the strategy with the NP mode, followed by RP and finally
POSC was found preferable from both the number of cumulative separations and of
baseline separations. Two approaches were considered for strategy fine tuning
using an additional set of eight racemic mixtures. In both approaches, seven of
the eight compounds were baseline resolved, on one of the examined columns at
either screening or optimization conditions of a mode. One approach was finally
preferred because of its lower workload.

Highlights

► 56 compounds and nine CSPs were used to update
strategies in three common HPLC modes. ► An HPLC chiral method development
strategy that combines NPLC, RPLC and POSC modes was defined. ► Success rate:
all compounds were separated with the updated strategy in less experiments. ►
The updated strategy was fine tuned.

A microflow chemiluminescence (CL) sensor for determination of dibutyl
phthalate (DBP) based on magnetic molecularly imprinted polymer (MMIP) as
recognition element was fabricated. Briefly, a hydrophilic molecularly imprinted
polymer layer was produced at the surface of Fe3O4@SiO2 magnetic nanoparticles
(MNPs) via combination of molecular imprinting and reversible stimuli responsive
hydrogel. In this protocol, the initial step involved co-precipitation of
Fe2+ and Fe3+ in an ammonia solution. Silica was then
coated on the Fe3O4 nanoparticles using a sol–gel method to obtain silica shell
magnetic nanoparticles. The MMIP was synthesized using methacrylic acid (MAA) as
functional monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker
and 2, 2-azobisisobutyronitrile (AIBN) as initiator in chloroform. Then the
synthesized MMIP and magnetic non-molecular imprinted polymers (MNIP) were
employed as recognition by packing into lab-made straight shape tubes, connected
in CL analyzer for establishing the novel sensor with a single channel syringe
pump. And a mixer for hydrolyzing of DBP was followed. Based on this experiment
principle, DBP was determined indirectly. And the MMIP showed satisfactory
recognition capacity to DBP, resulting to the wide linear range of
3.84×10−8 to 2.08×10−5 M and the low detection limit of
2.09×10−9 M (3σ) for DBP. The relative standard deviation (RSD) for
DBP (3.20×10−6 M) was 1.40% (n =11). Besides improving sensitivity
and selectivity, the sensor was reusable. The proposed DBP–MMIP–CL sensor has
been successfully applied to determine DBP in drink samples.

Graphical abstract

Highlights

► Fe3O4@SiO2 was used as
support for easier to control. ► Microscale Syringe Pump was used for saving
reagent. ► A mixer for hydrolyzing was used for
chemiluminescence.

In this work, a dispersive liquid–liquid microextraction (DLLME)
procedure combined with ultra-high performance liquid chromatography with
diode-array detection was developed to determine 25 antibiotics in mineral and
run-off waters. Optimum DLLME conditions (5mL of water at pH=7.6, 20% (w/v)
NaCl, 685μL of CHCl3 as extractant solvent, and 1250μL of ACN as disperser
solvent) allowed the repeatable, accurate and selective determination of 11
sulfonamides (sulfanilamide, sulfacetamide, sulfadiazine, sulfathiazole,
sulfadimidin, sulfamethoxypyridazine, sulfadoxine, sulfamethoxazole,
sulfisoxazole, sulfadimethoxine and sulfaquinoxaline) and 14 quinolones
(pipemidic acid, marbofloxacin, fleroxacin, levofloxacin, pefloxacin,
ciprofloxacin, lomefloxacin, danofloxacin, enrofloxacin, sarafloxacin,
difloxacin, moxifloxacin, oxolinic acid and flumequine). The method was
validated by means of the obtention of calibration curves of the whole method as
well as a recovery study at two levels of concentration. The LODs of the method
were in the range 0.35–10.5μg/L with recoveries between 78% and 117%.

Graphical abstract

Highlights

► A DLLME–UHPLC-DAD
method was developed to determine antibiotics in water. ► A total of 25
compounds (11 sulfonamides and 14 quinolones) was analyzed. ► Relative
recoveries values of the method were between 74% and 117%. ► The procedure is
simple, fast and reliable to determine the selected antibiotics.

Oral squamous cell carcinoma (OSCC) is an aggressive cancer and its
occurrence is closely related to betel nut chewing in Taiwan. However, there are
few prognostic and diagnostic biomarkers for this disease especially for its
association with betel nut chewing. Recent progresses in quantitative proteomics
have offered opportunities to discover plasma proteins as biomarkers for
tracking the progression and for understanding the molecular mechanisms of OSCC.
In present study, plasma samples from OSCC patients with at least 5-year history
of betel nut chewing and healthy donors were analyzed by fluorescence
2D-DIGE-based proteomic analysis. Totally, 38 proteins have been firmly
identified representing 13 unique gene products. These proteins mainly function
in inflammatory responses (such as fibrinogen gamma chain) and transport
(Apolipoprotein A–I). Additionally, the current quantitative proteomic approach
has identified numerous OSCC biomarkers including fibrinogen (alpha/beta/gamma)
chain, haptoglobin, leucine-rich alpha-2-glycoprotein and ribosomal protein S6
kinase alpha-3 (RSK2) which have not been reported and may be associated with
the progression and development of the disease. In summary, this study reports a
comprehensive patient-based proteomic approach for the identification of
potential plasma biomarkers in OSCC. The potential of utilizing these markers
for screening and treating OSCC warrants further investigations.

Psoralea corylifolia L. (Fabaceae) is a traditional Chinese medicine
with many beneficial effects in medical therapies. Bakuchiol was the main active
ingredient of Psoralea corylifolia L. In this study, a novel method of
pre-column derivatization with dansyl chloride followed by analysis of ultra
high-performance liquid chromatographic–tandem mass spectrometry (UHPLC–MS/MS)
was established and validated for quantification of bakuchiol in rat plasma. The
linearity of this approach was confirmed to be within the concentration range of
0.5–1000ng/mL and the lower limit of quantification was at 0.5ng/mL. The total
analysis time was 1.5min for each pretreated sample. Also, the precision,
accuracy, stability, recovery and matrix effect of this method were proved to
meet the requirements for bioanalysis. The intravenous and oral pharmacokinetic
profiles of bakuchiol were obtained by utilizing this approach. The oral
bioavailability of bakuchiol in rats (3.2%) was identified.

Graphical abstract

Highlights

A novel method of pre-column derivatization with
dansyl chloride followed by analysis of ultra high-performance liquid
chromatographic–tandem mass spectrometry (UHPLC–MS/MS) was established and
validated for quantification of bakuchiol in rat plasma. The intravenous and
oral pharmacokinetic profiles of bakuchiol were obtained by utilizing the
established method. ► An UHPLC–MS/MS method with
pre-column derivatization was built for bakuchiol. ► The method demonstrated
high sensitivity, wide linear range and short runtime. ► The method was used to
explore the pharmacokinetic profile of bakuchiol in rats. ► The oral
bioavailability of bakuchiol (3.2%) was reported for the first
time.

Over the last two decades, a growing number of scientific evidences
highlighted the potential therapeutic value of several structures of
aminoglycoside antibiotics (including gentamicin and G418) for the treatment of
various genetic diseases caused by nonsense mutations. These findings resulted
in a fast evolvement of synthetic derivatives of aminoglycosides which were
shown to be more target specific and less toxic than the clinically used
antibiotics. The emerging progress in drug design and development has
necessitated the urge to develop a fast, easy and accurate procedure for the
determination of these potential therapeutic agents in various biologically
derived matrices. Here we describe the preparation of a generic polyclonal
antibody that was used for the development of homologous and heterologous
immunoassays for the detection of a wide range of natural and synthetic
aminoglycoside derivatives, highlighted today as potential therapeutic agents
for the treatment of various genetic diseases. A common two-ring scaffold, NB82,
present in the majority of compounds exhibiting potent biological activity, was
used as a generic immunization hapten for the immunization of two rabbits. By
using a series of chemical steps, NB82 was selectively conjugated via the N-1
position through glutaric acid linker to a carrier protein. Sensitivity (I 50)
values for the recognition of three representative compounds NB82, NB84 and
NB124 were determined to be 10±3ngmL−1, 0.5±0.04μgmL−1 and
1±0.12μgmL−1, respectively. Limits of detection were determined to be
1±0.3ngmL−1 for NB82, 20±7ngmL−1 for NB84 and
15±8ngmL−1 for NB124. The developed assays were further exploited for
the in vivo monitoring of the therapeutic compounds in mice serum. Serum
experimentations exhibited similar detection limits as observed for the PBS
calibration experiments, demonstrating no interference with assays sensitivity,
with rather high recovery ratios ranging from 92 to 107% in whole blood samples.

Graphical abstract

Highlights

► A broad-specific ELISA
for the detection of aminoglycosides with 6′-OH was developed. ► These 6′-OH
aminoglycosides are best candidates for the treatment of genetic diseases. ► A
two-ring scaffold was selectively conjugated to a carrier protein at N-1
position. ► A generic antibody allowed highly sensitive monitoring of
therapeutic agents in vivo. ► The assay will aid in further development of
therapeutic compounds in clinic.

The metabolites and pharmacokinetics of ganoderic acid C2 (GAC2), a
bioactive triterpenoid in Ganoderma lucidum in rat plasma were investigated by
high-performance liquid chromatography coupled with electrospray ionization
tandem mass spectrometry (HPLC–ESI-MS/MS). Totally, ten minor phase I
metabolites of GAC2 were characterized after oral administration of GAC2, on the
basis of their mass fragmentation pathways or direct comparison with authentic
compounds by high-performance liquid chromatography coupled with diode array
detection and electrospray ion trap tandem mass spectrometry
(HPLC–DAD–ESI-MS n ), and liquid chromatography coupled with
electrospray ionization hybrid ion trap and time-of-flight mass spectrometry
(LC–ESI-IT-TOF/MS) methods. Moreover, a rapid and specific method for
quantification of GAC2 in rat plasma after oral administration was developed by
using a liquid–liquid extraction procedure and HPLC–ESI-MS/MS analysis. It is
the first time to report the metabolites and pharmacokinetics of GAC2.

Graphical abstract

Highlights

Proposed metabolic pathways of ganoderic acid C2
(M0) in rats. ► Ten minor phase I metabolites were
characterized. ► A rapid quantification method was developed by LC–MS/MS. ► The
metabolites and pharmacokinetic of GAC2 were reported firstly.

HPLC 2013 - Hobart

SPEC 2014

ISC 2014

Introductory Video

News Now

Communicating science and healthcare

Communicating science and healthcare

SPECIAL ISSUE - OMICS

Thematic special issue edited by Roma Tauler. Click on the cover to access this issue on Science Direct.

Owlstone

SPECIAL ISSUE - EXTECH 2009

A selection of papers presented at the 11th International Symposium on Advances in Extraction Technologies, Rapid City, SD, USA, 4-7 October 2009. Edited by Douglas Raynie and Janusz Pawliszyn. Click on the cover to access this issue on Science Direct.

SPECIAL ISSUE - 11th HTC 2010

Click cover to access the Science Direct link to this issue with selected papers from the 11th HTC, Bruges, Belgium, 26-29 January 2010.

SPECIAL ISSUE!

CLICK COVER FOR BIOLOGICAL MONITORING AND ANALYTICAL TOXICOLOGY IN OCCUPATIONAL AND ENVIRONMENTAL MEDICINE

Optical Biosensors by Ligler and Taitt - Click the cover to order

Optical Biosensors, 2ed describes the principles of successful systems, examples of applications, and evaluates the advantages and deficiencies of each. It also addresses future developments on two levels: possible improvements in existing systems and emerging technologies that could provide new capabilities in the future. The book is formatted for ease of use and is therefore suitable for scientists and engineers, students and researcher at all levels in the field.

Comprehensive Chemometrics - Click on the cover to learn more ...

features contributions of leading experts from 21 countries, under the guidance of the Editors-in-Chief and a team of specialist Section Editors: L. Buydens; D. Coomans; P. Van Espen; A. De Juan; J.H. Kalivas; B.K. Lavine; R. Leardi; R. Phan-Tan-Luu; L.A. Sarabia; and J. Trygg

Handbook of Process Chromatography

Since the publication of the first edition in 1997, the biotechnology and biologics industries have gained extensive knowledge and experience in downstream processing using chromatography and other technologies associated with recovery and purification unit operations. This book will tie that experience together for the next generation of readers.